JP2779280B2 - Laminated polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laminated polyester film for a magnetic recording medium , and more particularly to a biaxially oriented laminated polyester film useful as a base film for a high density magnetic recording medium.

[0002]

2. Description of the Related Art Polyester films typified by polyethylene terephthalate films have excellent mechanical properties, chemical properties and thermal properties and are used for a wide range of applications. Particularly, it is widely used as a base film of a magnetic recording medium.

By the way, polyester films are often required to have different properties on both surfaces, for example, it is required that one surface be a smooth surface and the other surface be a smooth surface. Further, further improvement in the surface properties of the polyester film is required.

As a means for improving the surface characteristics of a polyester film, a method of laminating different kinds of polyester films is known, and Japanese Patent Application Laid-Open Nos. 61-278022, 62-108053, and 63-120646.
JP-A-63-108529, JP-A-63-872
No. 31, JP-A-63-197643, JP-A-63-2
Many proposals such as 12549 have been made.

[0005]

However, the following problems remain to be solved in these laminated films of different polyesters. (1) When used as a base film for a magnetic recording tape or a flexible disk The layers of the base film (layers of different polyester layers) are peeled off when the tape runs or when a repeated external force such as a head touch of the flexible disk is applied. May be. (2) Since different types of polyesters having different properties are laminated, for example, in a two-layer film, the film is liable to curl due to a bimetallic effect,
When a magnetic tape is used, a cupping phenomenon may occur. (3) When immersed in water, a solvent, or the like, troubles such as peeling of the film of each layer from the boundary surface of the laminate may occur. (4) When used as a base film for magnetic recording, a magnetic layer is often applied to the base film and then calendered. However, in this step, the base film may be peeled off due to heat and shear applied to the base film. .

[0006]

The present invention has the following arrangement to attain the object.

A biaxially oriented laminated film in which a polyester (A) film layer and a different polyester (B) film layer are laminated, wherein the polyester (A) and the polyester (B) are provided between the two film layers. A laminated polyester film for a magnetic recording medium , provided with a layer having a thickness of 0.03 to 1.0 [mu] m, which is made of the above copolymer.

In the present invention, the polyester constituting the film is preferably exemplified by polyethylene-2,6-naphthalate, polyethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate and the like.

This polyethylene-2,6-naphthalate contains naphthalenedicarboxylic acid as a main acid component.
A small amount (preferably 20 mol% or less) of another dicarboxylic acid component may be copolymerized, and ethylene glycol is used as a main glycol component, but a small amount (preferably 20 mol% or less) of another glycol component is copolymerized. It is a polymer that may be polymerized. Examples of dicarboxylic acids other than naphthalenedicarboxylic acid include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, and benzophenone dicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecane dicarboxylic acid. And alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. As glycol components other than ethylene glycol, for example, 1,3-propanediol,
1,4-butanediol, 1,6-hexanediol,
Neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol and the like can be mentioned. In addition, a stabilizer, a coloring agent, a lubricant,
It may be one containing additives such as a matting agent.

[0010] Such polyethylene-2,6-naphthalate is usually produced by a known method by a melt polymerization method. At this time, additives such as a catalyst can be optionally used as needed.

The intrinsic viscosity of polyethylene-2,6-naphthalate is preferably in the range of 0.45 to 0.90.

The polyethylene terephthalate contains terephthalic acid as a main acid component, but a small amount (preferably 20 mol% or less) of another dicarboxylic acid component may be copolymerized. But a small amount (preferably 20 mol% or less)
Is a polymer which may be copolymerized with other glycol components. Examples of dicarboxylic acids other than terephthalic acid include, for example, naphthalenedicarboxylic acid, isophthalic acid, diphenylsulfonedicarboxylic acid, aromatic dicarboxylic acids such as benzophenonedicarboxylic acid, succinic acid, adipic acid, sebacic acid, and aliphatic dicarboxylic acids such as dodecanedicarboxylic acid. And alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. Examples of glycol components other than ethylene glycol include 1,3-propanediol and 1,4-propanediol.
Butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol and the like. Further, additives such as a stabilizer, a coloring agent, a lubricant, a matting agent, and the like may be blended in the polymer.

Such polyethylene terephthalate is usually produced by a known method by a melt polymerization method. At this time, additives such as a catalyst can be optionally used as needed.

The intrinsic viscosity of polyethylene terephthalate is preferably in the range of 0.45 to 0.90.

The poly-1,4-cyclohexylene dimethylene terephthalate contains terephthalic acid as a main acid component, but may be copolymerized with a small amount (preferably 20 mol% or less) of another dicarboxylic acid component. Well, one, four
-A polymer in which cyclohexanedimethanol is the main glycol component, but a small amount (preferably 20 mol% or less) of another glycol component may be copolymerized. Examples of dicarboxylic acids other than terephthalic acid include, for example, naphthalenedicarboxylic acid, isophthalic acid, diphenylsulfonedicarboxylic acid, aromatic dicarboxylic acids such as benzophenonedicarboxylic acid, succinic acid, adipic acid, sebacic acid, and aliphatic dicarboxylic acids such as dodecanedicarboxylic acid. And alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. As glycol components other than 1,4-cyclohexanedimethanol, for example, ethylene glycol, 1,3-
Propanediol, 1,4-butanediol, 1,6-
Hexanediol, neopentyl glycol, p-xylylene glycol and the like can be mentioned. Said 1,
4-Cyclohexanedimethanol can be produced, for example, by a method of producing it by catalytic reduction of dimethyl terephthalate or terephthalic acid, but there is no problem even if it is produced by either method. The ratio of the cis-form to the trans-form of 1,4-cyclohexanedimethanol is not particularly limited, but a cis-form / trans-form in the range of 4/6 to 0/10 is preferable.

Further, additives such as a stabilizer, a colorant, a lubricant, a matting agent and the like may be blended in the polymer.

Such poly-1,4-cyclohexylene dimethylene terephthalate is usually produced by a known method by a melt polymerization method. At this time, additives such as a catalyst can be optionally used as needed.

The intrinsic viscosity of poly-1,4-cyclohexylene dimethylene terephthalate is preferably in the range of 0.45 to 0.90.

The inert solid fine particles (lubricant) that can be contained in the polyester in the present invention are preferably (1) silicon dioxide (including hydrate, diatomaceous earth, silica sand, quartz, etc.); (2) Alumina; (3) SiO ₂
Silicates containing 30% by weight or more of components (for example, amorphous or crystalline clay minerals, aluminosilicates (including calcined products and hydrates), hot asbestos, zircon, fly ash, etc.); (4) Mg , Zn, Zr, and Ti oxides;
(5) Ca and Ba sulfates; (6) Li, Na and Ca phosphates (including mono- and di-hydrogen salts);
(7) Li, Na and K benzoates; (8) Ca,
Terephthalates of Ba, Zn, and Mn; (9) Mg,
Ca, Ba, Zn, Cd, Pb, Sr, Mn, Fe, C
(10) Ba and Pb chromates; (11) carbon (eg, carbon black,
(12) glass (for example, glass powder,
(13) Ca and Mg carbonates;
(14) Fluorite and (15) ZnS are cited. More preferably, silicon dioxide, silicic anhydride, hydrated silicic acid, aluminum oxide, aluminum silicate (calcined product,
Hydrate, etc.), monolithium phosphate, trilithium phosphate,
Sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, lithium benzoate, double salts of these compounds (including hydrates), glass powder, clay (including kaolin, bentonite, clay, etc.), talc, diatomaceous earth, Examples thereof include calcium carbonate. Particularly preferably, silicon dioxide,
Examples include titanium oxide and calcium carbonate.

The stabilizer is preferably a phosphorus compound such as phosphoric acid, phosphorous acid, or an ester thereof, and the lubricating agent is preferably titanium dioxide, silica, barium sulfate or the like.

The laminated film of the present invention comprises at least two kinds of the above-mentioned polyesters, for example, polyethylene-2,6-naphthalate and polyethylene terephthalate, polyethylene-2,6-naphthalate and poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene A structure in which a film of polyester (A) and a film of polyester (B) are laminated using terephthalate and poly-1,4-cyclohexylene dimethylene terephthalate as polyester (A) and polyester (B).
Then, a layer made of a copolymer of polyester (A) and polyester (B) is interposed between the two film layers. Such a copolymer is prepared, for example, by melt-mixing a polyester (A) and a polyester (B) and copolymerizing them by a transesterification reaction or a redistribution reaction. It can be produced by a conventionally known method such as a method of producing a copolymerized polyester by mixing in a state and changing the mixing ratio of each component.
Among these, the former method of melt-mixing the polyester (A) and the polyester (B) and copolymerizing them is simple and preferable.

The laminated film in the present invention is formed by laminating different types of polyester film layers, and the number of laminations may be two or more. That is, for example, polyethylene terephthalate and polyethylene-2,6
-Two layers of naphthalate or three layers of polyethylene terephthalate as a core layer and poly-1,4-cyclohexylene dimethylene terephthalate laminated on both outer surfaces thereof may be used. The point is to interpose a layer of a copolymer of these polyesters between layers of these different polyesters, that is, polyester (A) and polyester (B).

Polyester (A) and polyester (B)
The method of interposing a layer of these polyester copolymers between the layers is not particularly limited, but is preferably interposed by a coextrusion method. That is, dried pellets of polyester (A) and polyester (B) are prepared, and pellets of both polyesters are mixed at a desired ratio, and melt-mixed at a temperature for a predetermined time in a melt extruder to obtain a copolymerized pellet. prepare. These three types of polyester pellets are fed to individual extruders and melted so that a three-layer coextrusion die forms a copolymer layer in the middle layer between the polyester (A) layer and the polyester (B) layer. It is good to extrude.

The extruding method is such that the polymers are merged in a polymer pipe being extruded, or these polymers are merged in an extrusion die having three layers in the thickness direction to form a single sheet, which is then cast on a casting drum. Extrude and cool.

The thickness of the copolyester layer interposed between the polyesters (A) and (B) is 0.03 μm to 1.0 μm in the final product (biaxially oriented film) . This
If the thickness of the polyester is more than 1.0 μm, polyester (A),
This is not good because the mechanical properties originally possessed by (B) are impaired. On the other hand, if the thickness of the copolyester layer is less than 0.03 μm, the effect of interposing the copolyester layer is almost undesirably lost.

The composition of the copolymerized polyester is 60: 4 as a ratio of the polyester (A) and the polyester (B).
It is preferable to take 0 to 40:60. For example, if the polyester (A) is polyethylene-2,6-naphthalate (P
EN-2, 6), when the polyester (B) is polyethylene terephthalate (PET), PET and PEN-
PET / PEN-2,6 = 60 as the ratio of the components 2,6
It is preferably in the range of / 40 to 40/60. If the ratio is out of the range, it is not preferable because the function of strongly bonding the interface is lost even if the copolymer is interposed between the layers of PEN-2, 6 and PET.

Since the thus obtained laminated film is in an unstretched state, it is further subjected to stretching orientation and heat setting.
The stretching orientation treatment may be either sequential biaxial stretching or simultaneous biaxial stretching, but the former is more preferred. The stretching method may be a known method. For example, longitudinal stretching can be performed while heating between two rolls having a difference in peripheral speed, and transverse stretching can be performed by gripping both ends of a film with a clip and heating the clip row. Stretching can be performed by increasing the line interval. As the stretching method, for example, a vertical-horizontal two-stage stretching or a vertical-horizontal-vertical-horizontal four-stage stretching method can be applied.

[0028]

The present invention will be further described below with reference to examples.

[0029]

Example 1, Comparative Example 1 A polyethylene terephthalate (PET: polyester B) having an intrinsic viscosity of 0.60 dl / g (measured at 25 ° C. using orthochlorophenol as a solvent) substantially free of a lubricant, and Polyethylene-2 having an intrinsic viscosity of 0.58 dl / g containing 0.3% by weight of silica particles having an average particle diameter of 0.1 μm and 0.020% by weight of calcium carbonate particles having an average particle diameter of 0.6 μm.
6-Naphthalate rate (PEN: polyester A) was prepared. Each of these polymers was dried at 170 ° C and then melted at 310 ° C in a separate melt extruder. on the other hand,
These dry polymers are mixed in a weight ratio of 1: 1 and another 1
The mixture was melt-mixed with two melt extruders and kept at 310 ° C. for 10 minutes (PEN-PET copolymer). These polymers were supplied from a polymer pipe and extruded from an extrusion die having a five-layer structure. That is, PEN / PEN-PET copolymer / PET / PET-PEN copolymer / PEN
Extruded into a five-layer structure, combined and laminated in a die, extruded through a die slit into a casting drum cooled, and cooled to obtain an unstretched film.

The unstretched film is stretched 3.6 times in the vertical and horizontal directions.
× 3.6 times sequential stretching, heat fixing at 215 ° C, 75μ
Thus, a laminated film having a thickness of m was obtained. At this time, the extrusion amount of the polymer was adjusted so that the thickness of each layer of the five-layer structure was 10 / 1.0 / 53 / 1.0 / 10. (Example 1)

On the other hand, without interposing a copolymer of polyesters (A) and (B) between polyesters (A) and (B),
PEN / PET / PEN was extruded from an extrusion die having a three-layer structure to prepare a biaxially stretched film having a thickness of 75 μm in the same manner as described above. The thickness of each layer of this is PEN / PET /
It was adjusted so that PEN = 10/55/10. (Comparative Example 1) The biaxially oriented laminated film thus obtained was cut into a 10 cm mouth, immersed in water at room temperature for 1 hour, taken out, and subjected to a peeling test.

In the peeling test, it was examined whether or not the film was separated into three pieces by squeezing the cut end of the film with a finger.

The film of Example 1 did not peel at all, but the film of Comparative Example 1 peeled into three thin films. In addition, when these films were notched and pulled by hand in the front-rear direction, the film of Example 1 was torn almost straight in the direction of the notch,
It can be seen that the film of Comparative Example 1 was bent in the tearing direction or delaminated at the interface of the lamination, and the polyester (A) and (B) layers did not have good adhesion at the interface. only.

[0034]

Example 2, Comparative Example 2 Polyethylene having an intrinsic viscosity of 0.62 containing 0.15% by weight of silica particles having an average particle size of 0.1 μm and 0.16% by weight of calcium carbonate particles having an average particle size of 0.6 μm. -2,6-Naphthalate (PEN) and polyethylene terephthalate (PET) having an intrinsic viscosity of 0.62 and containing substantially no lubricant were melted in a separate melt extruder at 310 ° C. In another melt extruder, PEN having substantially the same intrinsic viscosity as above, substantially free of lubricant.
2,6 and PET as PET / PEN-2,6 = 55/4
5 (weight ratio) and kept at 310 ° C. for 10 minutes (PE
T-PEN copolymer). These molten polymers were extruded into a three-layer structure, merged in a die, extruded on a casting drum and cooled to obtain an unstretched PET / PET-PEN copolymer / PEN film.

This unstretched film is stretched 4.85 times in the machine direction at a temperature of 120 ° C. between two rolls having a difference in speed, and furthermore, it is 5.1 in a transverse direction at 145 ° C. by a tenter.
It was stretched 5 times and then heat-treated at 215 ° C. for 10 seconds.
Thus, a 6 μm-thick biaxially oriented polyester laminated film (thickness configuration: PEN / PET-PEN copolymer / PET = 5 / 0.2 / 0.8) was wound. (Example 2)

A 6 μm biaxially oriented polyester laminated film (thickness structure: PEN / PET = 5.2 /) was carried out in exactly the same manner as in Example 2 except that no PET-PEN copolymer layer was interposed between the three-layer films. 0.8).
(Comparative Example 2)

On the other hand, the following composition was put into a ball mill, kneaded and dispersed for 16 hours, and then 5 parts by weight of an isocyanate compound (Desmodur L manufactured by Bayer AG) was added.
A high-speed shearing dispersion was performed for 1 hour to obtain a magnetic paint. Composition of magnetic paint Acicular Fe particles 100 parts by weight Vinyl chloride-vinyl acetate copolymer 15 parts by weight (SREC 7A manufactured by Sekisui Chemical) Thermoplastic polyurethane resin 5 parts by weight Chromium oxide 5 parts by weight Carbon black 5 parts by weight Lecithin 2 parts by weight Part Fatty acid ester 1 part by weight Toluene 50 parts by weight Methyl ethyl ketone 50 parts by weight Cyclohexanone 50 parts by weight This magnetic paint is applied to one side of the above-mentioned laminated film on the polyethylene terephthalate side so as to have a coating thickness of 3 μm, and then a DC magnetic field of 2500 Gauss After performing an orientation treatment in the glass and drying by heating at 100 ° C., a super calender treatment (linear pressure: 200 kg / cm, temperature: 80 ° C.) was performed, and the film was wound up. The wound roll was allowed to stand for 3 days while being opened at 55 ° C.

The electromagnetic conversion characteristics and running durability of the tape obtained from the film of Example 2 were good. However, the tape obtained from the film of Comparative Example 2 had poor running durability. That is, when the tape was repeatedly run 200 times on the tape deck, peeling occurred between the base film layers at the end face of the tape.

[0039]

According to the present invention, the following effects can be obtained. 1. It is possible to prevent curling and cupping, which tend to occur in a laminated biaxially oriented polyester film of different polymers. 2. It is possible to provide a base film in which peeling between layers and delamination hardly occur even when a force such as repeated bending is applied. 3. For example, when used as a flexible disk, the base film has a flexible layer to improve head touch.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisashi Hamano 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture Inside the Sagamihara Research Center, Teijin Limited (56) References JP-A-3-39250 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) B32B 1/00-35/00

Claims (4)

(57) [Claims] 1. A biaxially oriented laminated film comprising a polyester (A) film layer and a different polyester (B) film layer laminated thereon, wherein the polyester (A) and the polyester (B) are provided between the two film layers. A laminated polyester film for a magnetic recording medium , comprising a layer having a thickness of 0.03 to 1.0 [mu] m made of the copolymer according to (1). 2. Polyester (A) is polyethylene-2,
The laminated polyester film for a magnetic recording medium according to claim 1, which is 6-naphthalate. 3. The laminated polyester film for a magnetic recording medium according to claim 2, wherein the polyester (B) is polyethylene terephthalate or poly-1,4-cyclohexylene dimethylene terephthalate. 4. Polyester (A) is polyethylene terephthalate and polyester (B) is poly-1,4-
The laminated polyester film for a magnetic recording medium according to claim 1, which is cyclohexylene dimethylene terephthalate.